Fix missing call to write barrier in static constructors of ref structs

src/coreclr/jit/importer.cpp

@@ -9797,9 +9797,9 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                     // Field's type is a byref-like struct -> address is not on the heap.
                     indirFlags |= GTF_IND_TGT_NOT_HEAP;
                 }
-                else
+                else if ((fieldInfo.fieldFlags & CORINFO_FLG_FIELD_STATIC) == 0)
                 {
-                    // Field's owner is a byref-like struct -> address is not on the heap.
+                    // Field's owner is a byref-like struct and the field is not static -> address is not on the heap.
                     CORINFO_CLASS_HANDLE fldOwner = info.compCompHnd->getFieldClass(resolvedToken.hField);
                     if ((fldOwner != NO_CLASS_HANDLE) && eeIsByrefLike(fldOwner))
                     {

src/tests/JIT/Regression/JitBlue/Runtime_125169/Runtime_125169.cs

@@ -0,0 +1,48 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using Xunit;
+
+public readonly struct ByteArrayWrapper
+{
+    public readonly byte[] _innerArray;
+
+    public ByteArrayWrapper(scoped in byte[] innerArray)
+    {
+        _innerArray = innerArray;
+    }
+}
+
+public readonly ref struct RefWrapper
+{
+    public static readonly ByteArrayWrapper _data = new ByteArrayWrapper(new byte[] { 0, 1, 2, 3, 4 });
+}
+
+public class Runtime_125169
+{
+    // Regression test for bug in JIT where ref struct static fields of reference type initialized in
+    // its static constructor were missing calls to JIT_ByRefWriteBarrier for each such static field.
+    [Fact]
+    public static void TestEntryPoint()
+    {
+        byte[][] arr = new byte[100][];
+        // Generate enough garbage
+        for (int i = 0; i < 100; i++)
+        {
+            arr[i] = new byte[100000];
+        }
+
+        ReadOnlySpan<byte> testSpan = new(RefWrapper._data._innerArray);
+        // Without the fix, the following GC.Collect call causes fatal error during heap verification with DOTNET_HeapVerify=1
+        GC.Collect(0);
+
+        // Prevent the compiler from optimizing out the loop above.
+        GC.KeepAlive(arr);
+
+        for (int i = 0; i < testSpan.Length; i++)
+        {
+            Assert.Equal(i, testSpan[i]);
+        }
+    }
+}

src/tests/JIT/Regression/Regression_ro_2.csproj

@@ -91,6 +91,7 @@
     <Compile Include="JitBlue\Runtime_124507\Runtime_124507.cs" />
     <Compile Include="JitBlue\Runtime_125041\Runtime_125041.cs" />
     <Compile Include="JitBlue\Runtime_125058\Runtime_125058.cs" />
+    <Compile Include="JitBlue\Runtime_125169\Runtime_125169.cs" />
     <Compile Include="JitBlue\Runtime_125301\Runtime_125301.cs" />
     <Compile Include="JitBlue\Runtime_125328\Runtime_125328.cs" />
   </ItemGroup>